﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

//引入命名空间
using System.IO.Ports;
using System.Threading;

namespace ModbusRTULib
{
    /// <summary>
    /// ModbusRTU通信库
    /// </summary>
    public class ModbusRTU
    {
        //串口对象
        private SerialPort serialPort = null;
        //构造方法
        public ModbusRTU()
        {

        }
        /// <summary>
        /// 有参数构造方法
        /// </summary>
        /// <param name="delay">接收报文延时</param>
        public ModbusRTU(int delay)
        {
            this.ReceiveDelay = delay;
        }

        //接收报文延时
        //private int ReceiveDelay { get; set; } //这样写，对延时时间没有限制，很容易出问题
        private int _receiveDelay = 100;
        public int ReceiveDelay
        {
            get
            {
                return _receiveDelay;
            }
            set
            {
                if (value < 10 || value > 200)
                {
                    _receiveDelay = 100;
                }
                else
                {
                    _receiveDelay = value;
                }
            }
        }

        //方法(打开串口、关闭串口、读取保持寄存器03H...、CRC校验
        /// <summary>
        /// 打开串口
        /// </summary>
        /// <param name="portName">串口号</param>
        /// <param name="baudRate">波特率</param>
        /// <param name="parity">校验位</param>
        /// <param name="dataBits">数据位</param>
        /// <param name="stopBits">停止位</param>
        public void Connect(string portName, int baudRate = 9600, Parity parity = Parity.None, int dataBits = 8, StopBits stopBits = StopBits.One)
        {
            //实例化串口对象
            serialPort = new SerialPort(portName, baudRate, parity, dataBits, stopBits);
            try
            {
                serialPort.Open();
            }
            catch (Exception ex)
            {
                throw new Exception("串口打开失败！原因：" + ex.Message);
            }
        }
        /// <summary>
        /// 关闭串口
        /// </summary>
        public void DisConnect()
        {
            if (serialPort != null && serialPort.IsOpen)
            {
                serialPort.Close();
            }
        }
        /// <summary>
        /// 读取保存寄存器，功能码03H
        /// </summary>
        /// <param name="slaveID">从站ID</param>
        /// <param name="startAddress">起始寄存器地址(10进制)</param>
        /// <param name="count">寄存器数量</param>
        /// <returns>只有数据的字节数组</returns>
        public byte[] ReadHoldingRegister(byte slaveID, int startAddress, int count)
        {
            //第一步： 封装【请求】报文
            byte[] sendBytes = new byte[8];
            sendBytes[0] = slaveID;
            sendBytes[1] = 0x03;
            sendBytes[2] = (byte)(startAddress / 256); //将int类型的地址,转换成字节高位
            sendBytes[3] = (byte)(startAddress % 256); //将int类型的地址,转换成字节低位
            sendBytes[4] = (byte)(count / 256);
            sendBytes[5] = (byte)(count % 256);
            //封装CRC校验
            byte[] crc = CRC16(sendBytes, 6); //校验前面6位
            sendBytes[6] = crc[0];
            sendBytes[7] = crc[1];

            //第二步： 发送【请求】报文
            byte[] receiveBytes = null;
            try
            {
                serialPort.Write(sendBytes, 0, sendBytes.Length); //发送报文，等待返回
                Thread.Sleep(ReceiveDelay); //接收缓冲，否则太快

                //第三步： 接收【应答】报文
                receiveBytes = new byte[serialPort.BytesToRead];
                serialPort.Read(receiveBytes, 0, receiveBytes.Length); //从缓冲区接收全部报文到指定数组
            }
            catch (Exception ex)
            {
                throw new Exception("发送或接收报文出现问题："+ex.Message);
            }

            //第四步： 解析【应答】报文
            int byteLength = 2 * count;
            if (receiveBytes.Length == 5 + byteLength) //报文长度必须合理
            {
                if (CheckCRC(receiveBytes) && receiveBytes[1] == 0x03 && receiveBytes[2] == byteLength)
                {
                    byte[] returnDataArray = new byte[byteLength];
                    //返回截取后只包括数据的数组(从索引3开始（去掉地址，功能码，字节计数），目的数组，从0开始，复制数据长度)
                    Array.Copy(receiveBytes, 3, returnDataArray, 0, byteLength);
                    return returnDataArray;
                }
                else return null;
            }
            else return null;
        }
        #region CRC校验【查表法，速度很快】
        private static readonly byte[] auchCRCHi = new byte[]
            {
            0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
            0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
            0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
            0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
            0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
            0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
            0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
            0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
            0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
            0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
            0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
            0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
            0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
            0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
            0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
            0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
            0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
            0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
            0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
            0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
            0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
            0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
            0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
            0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
            0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
            0x80, 0x41, 0x00, 0xC1, 0x81, 0x40
            }; //crc高位表
        private static readonly byte[] auchCRCLo = new byte[] //crc低位表
        {
            0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06,
            0x07, 0xC7, 0x05, 0xC5, 0xC4, 0x04, 0xCC, 0x0C, 0x0D, 0xCD,
            0x0F, 0xCF, 0xCE, 0x0E, 0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09,
            0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9, 0x1B, 0xDB, 0xDA, 0x1A,
            0x1E, 0xDE, 0xDF, 0x1F, 0xDD, 0x1D, 0x1C, 0xDC, 0x14, 0xD4,
            0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3,
            0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3,
            0xF2, 0x32, 0x36, 0xF6, 0xF7, 0x37, 0xF5, 0x35, 0x34, 0xF4,
            0x3C, 0xFC, 0xFD, 0x3D, 0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A,
            0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38, 0x28, 0xE8, 0xE9, 0x29,
            0xEB, 0x2B, 0x2A, 0xEA, 0xEE, 0x2E, 0x2F, 0xEF, 0x2D, 0xED,
            0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26,
            0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60,
            0x61, 0xA1, 0x63, 0xA3, 0xA2, 0x62, 0x66, 0xA6, 0xA7, 0x67,
            0xA5, 0x65, 0x64, 0xA4, 0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F,
            0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB, 0x69, 0xA9, 0xA8, 0x68,
            0x78, 0xB8, 0xB9, 0x79, 0xBB, 0x7B, 0x7A, 0xBA, 0xBE, 0x7E,
            0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5,
            0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71,
            0x70, 0xB0, 0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92,
            0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C,
            0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E, 0x5A, 0x9A, 0x9B, 0x5B,
            0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89, 0x4B, 0x8B,
            0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C,
            0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42,
            0x43, 0x83, 0x41, 0x81, 0x80, 0x40
         };
        private byte[] CRC16(byte[] pucFrame, int usLen)// 低8 高8
        {
            int i = 0;
            byte[] res = new byte[2] { 0xFF, 0xFF };

            ushort iIndex = 0x0000;

            while (usLen-- > 0)
            {
                iIndex = (ushort)(res[0] ^ pucFrame[i++]);
                res[0] = (byte)(res[1] ^ auchCRCHi[iIndex]);  // 低
                res[1] = auchCRCLo[iIndex]; // 高
            }
            return res;
        }
        private bool CheckCRC(byte[] value)
        {
            if (value == null) return false;
            if (value.Length <= 2) return false;
            int length = value.Length;
            byte[] buf = new byte[length - 2];
            Array.Copy(value, 0, buf, 0, buf.Length);

            byte[] CRCbuf = CRC16(buf, buf.Length);
            if(CRCbuf[0] == value[length - 2] && CRCbuf[1] == value[length - 1])
            {
                return true;
            }
            return false;
        }
        #endregion
    }
}
